Ok
So if I do not misunderstand you
You have tested with another device and the serial cable works there but when you connect to the firewall it stops working.
and you have tested with different speeds so it is not a configuration problem.
the port is for all purposes dead.
check to se that the pegs in the port is not bent or destroyed.
if they are, then you can gently try to reset them. be gentle and do not break them off.
If it is under contract then open a tac case to get a replacement.
If it is not under contract order a new one and scrap the old.
The serial port is one of the most important ports on the firewall I would not consider one with a broken serial port to be safe to run in a production environment.
The management port is just a management port by name.
it can be used as a management port or it can be used as a normal network port. (fx we try to use it for failover link if needed)
it is an ethernet port just as any of the others, you can try to attach a computer on that port and se if you get a DHCP address assigned to you.
if you get an address try to use https and the ip address that served you the DHCP address.
you might get a warning that the certificate is not a proper one, ignore that warning and choose to either download or run the ASDM on the devicec, (hopefully you will have the username and password for the device).
there is some stuff you can do with the flashcard if you have an equal type of firewall, but lets not go into them unless we realy have to.
Good luck
HTH
